This invention relates to an adjustable liner for securely supporting elongated work elements centered within a machine tool in a relatively undistorted posture.
More specifically, this invention relates to a hollow liner, as typically utilized in a wide number of machine applications, for handling and feeding tubular or bar stock so that the axial centerline of the work remains concentrically aligned with the working centerline of the machine. In order to accommodate work elements of different sizes and shapes, as well as to allow the work to be fed through the machine, the liner is conventionally provided with one or more clamping devices which can be automatically opened and closed about the in process work to permit the desired machine operations to be carried out. Maintaining the work centered, while at the same time holding the work securely against the action of a tool or the like, has heretofore been a problem in the art.
One type of liner in use involves a collapsible sleeve containing a series of inwardly deformed sections that are adapted to collapse into holding contact against a workpiece contained within the sleeve. Actuation of the device is achieved by either applying a compressive force to both ends of the sleeve of sufficient magnitude to collapse the sections or by twisting the ends of the sleeve to achieve the same results. Although the collapsible sleeve has been shown to operate well in practice, it nevertheless is subject to material limitations in that the deforming and holding characteristics of the sleeve tend to change with usage. This type of liner is disclosed in U.S. Pat. No. 3,927,585.
In U.S. Pat. No. 4,058,036 an improved liner is disclosed in which a plurality of pivoted rings are mounted within an elongated sleeve so as to encompass a work element supported therein. In practice, the rings are rotated about their respective pivots so that the upper and lower rim surfaces, in regard to the pivot, bite into the work element to hold it in place. By mounting the pivots along a diameter of the sleeve, the work element is automatically centered under the influence of the clamping ring. However, because the two clamping surfaces of each ring are offset some distance in an axial direction, the rings tend to bend or otherwise crimp the work therebetween. As a consequence, the ring-like clamps can deform a slender or thin walled element thus rendering it unsuitable for use.